Occipito-cervical fixation assembly and method for constructing same

ABSTRACT

An implantable orthopedic assembly comprises an occipital plate and one or more repositionable clamping assemblies for securing a stabilizing rod to the plate. When unlocked, the clamping assembly may be laterally and rotationally repositioned along a supporting rail. Locking occurs when a stabilizing rod is secured in the clamping assembly. The rod exerts a force upon a locking component, causing the locking component to exert a force upon the supporting rail. This force pulls a surface of the clamping assembly base into contact with the rail, effectively locking the clamping assembly base at a fixed position. The clamping assembly may further comprise a loading component to exert a stabilizing force on the locking component, keeping the clamping assembly positionally stable while adjustments are made prior to locking.

TECHNICAL FIELD

The disclosed embodiments relate generally to orthopedic implantabledevice technology, and more specifically to implantable devices for usein stabilizing the occipito-cervical junction and the cervical spine.

BACKGROUND

In the human body, the lower back portion of the skull is known as theocciput, and the neck vertebrae located closest to the skull are knownas the cervical spine. Critical neurological and vascular structuresdescending from the brain into the spinal column pass through thejunction between the skull and the cervical spine (the occipito-cervicaljunction). When disease or traumatic injury threatens the stability ofthe cervical spine and/or the occipito-cervical junction, surgicalintervention may be required to protect these critical structures.

Implantable occipito-cervical fixation systems that providestabilization and/or promote fusion of the occipito-cervical junctionare known in the art. However, existing systems may be difficult andtime-consuming to adjust, and often fail to provide desirableconfigurability options. A need exists for an implantableoccipito-cervical fixation system that simplifies and streamlinessurgical placement procedures and provides greater configurability toaccommodate varying patient anatomies during surgical placement.

BRIEF SUMMARY

Disclosed herein are various embodiments of an implantable orthopedicassembly generally comprising an occipital plate and one or morerepositionable clamping assemblies for securing a stabilizing rod at anonzero distance from a frictional surface of the plate. The frictionalsurfaces can comprise any of a variety of surfaces, including knurledmetal, machined feature in metal, abrasive grit blasted metal, metalparticles deposited on metal, bead blasted metal, and machined metalwith surface roughness. One or more rails may extend laterally from theplate to support the clamping assemblies.

Embodiments of the clamping assembly generally comprise a basecomponent, a body component, and a locking component. When unlocked, theclamping assembly may be laterally repositioned along the supportingrail and may also be rotationally repositioned. Locking occurs when astabilizing rod is secured in the clamping assembly. The rod exerts aforce upon the locking component, causing the locking component to exerta force upon the supporting rail. This force pulls a frictional surfaceof the clamping assembly base into a frictional surface of the rail,effectively locking the clamping assembly base at a fixed position. Theclamping assembly may further comprise a loading component to exert astabilizing force on the locking component, keeping the clampingassembly positionally stable while adjustments are made prior tolocking.

Embodiments of the occipital plate may comprise grooves for facilitatingcontouring of the plate. The plate may also comprise one or moreapertures for receiving bone fasteners that may secure the plate to theocciput. The apertures may be circular or non-circular, may becountersunk, and may be orthogonal or non-orthogonal to the plate. Theplate may also comprise notches or other instrument interfaces forfacilitating manipulation of the plate prior to and/or during placement.

Also disclosed herein are various embodiments of a method ofconstructing an implantable orthopedic assembly as described above. Themethod generally comprises positioning a locking component within thebody of a clamping assembly, positioning a frictional surface of a railagainst a frictional surface of the base of the clamping assembly,uniting the body with the base such that the rail contacts the lockingcomponent, and securing the base to the body. Embodiments may alsocomprise positioning a loading component between the locking componentand the body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a top view of an embodiment of an implantableoccipito-cervical fixation assembly.

FIG. 1B illustrates a bottom view of an embodiment of an implantableoccipito-cervical fixation assembly.

FIG. 1C illustrates a cross-sectional view of an embodiment of animplantable occipito-cervical fixation assembly.

FIG. 2A illustrates a top view of an embodiment of an implantableoccipito-cervical fixation assembly.

FIG. 2B illustrates a bottom view of an embodiment of an implantableoccipito-cervical fixation assembly.

FIG. 2C illustrates a cross-sectional view of an embodiment of animplantable occipito-cervical fixation assembly.

FIG. 3 illustrates an embodiment of an occipital plate component of animplantable occipito-cervical fixation assembly.

FIG. 4 illustrates an embodiment of a clamping assembly component of animplantable occipito-cervical fixation assembly.

FIG. 5 illustrates an embodiment of an occipital plate component of animplantable occipito-cervical fixation assembly.

FIG. 6A illustrates an embodiment of a clamping assembly component of animplantable occipito-cervical fixation assembly.

FIG. 6B illustrates a cross-sectional view of an embodiment of aclamping assembly component of an implantable occipito-cervical fixationassembly.

DETAILED DESCRIPTION

One embodiment of an implantable occipito-cervical fixation assembly 100is illustrated in FIGS. 1A, 1B, and 1C. A top view of this embodiment isillustrated in FIG. 1A. A bottom view of this embodiment is illustratedin FIG. 1B. A cross-sectional view of this embodiment is illustrated inFIG. 1C. Occipital plate 110 supports one or more clamping assemblies120. Although FIGS. 1A, 1B, and 1C illustrate embodiments with twoclamping assemblies, embodiments with a single clamping assembly andembodiments with three or more clamping assemblies are contemplated.Occipital plate 110 may be secured to an occiput, and a stabilizing rod(not shown) may be secured in one or more clamping assemblies 120 toprovide stabilization and/or promote fusion of the occipito-cervicaljunction.

Each clamping assembly 120 has at least two states: locked and unlocked.In its unlocked state, each clamping assembly 120 is movably attached toa portion of occipital plate 110, and may be adjusted positionally priorto locking. For example, clamping assembly 120 may be repositionedlaterally by sliding clamping assembly 120 along a portion of occipitalplate 110. For another example, clamping assembly 120 may berepositioned rotationally by turning clamping assembly 120 about an axissubstantially orthogonal to occipital plate 110. In its unlocked state,clamping assembly 120 may be prevented from disconnecting completelyfrom occipital plate 110, for example by a retaining element located onoccipital plate 110 or on clamping assembly 120. In some embodiments, anunlocked clamping assembly 120 may be fully disconnected from occipitalplate 110. Furthermore, some embodiments of clamping assembly 120 may beconfigured with a loading component to positionally stabilize unlockedclamping assembly 120, allowing for more precise positioning prior tolocking.

Once clamping assembly 120 is properly positioned, clamping assembly 120may be locked in place. Once locked, clamping assembly 120 is rigidlyfixed to occipital plate 110, and further lateral and rotationalmovement of clamping assembly 120 relative to occipital plate 110 isprecluded. Locking occurs when a stabilizing rod (not shown) is insertedinto clamping assembly 120. The adjustability of clamping assembly 120relative to occipital plate 110 prior to locking, along with thesimplicity of the locking procedure, allows the installation ofoccipito-cervical fixation assembly 100 to be quickly and easilycustomized to accommodate variations in patient anatomy as well asvariations in desired therapeutic benefits.

Another embodiment of an implantable occipito-cervical fixation assembly200 is illustrated in FIGS. 2A, 2B, and 2C. A top view of thisembodiment is illustrated in FIG. 2A. A bottom view of this embodimentis illustrated in FIG. 2B. A cross-sectional view of this embodiment isillustrated in FIG. 2C. Occipital plate 210 supports one or moreclamping assemblies 220. Although FIGS. 2A, 2B, and 2C illustrateembodiments with two clamping assemblies, embodiments with a singleclamping assembly and embodiments with three or more clamping assembliesare contemplated. Occipital plate 210 may be secured to an occiput, anda stabilizing rod (not shown) may be secured in one or more clampingassemblies 220 to provide stabilization and/or promote fusion of theoccipito-cervical junction.

Each clamping assembly 220 has at least two states: locked and unlocked.In its unlocked state, each clamping assembly 220 is movably attached toa portion of occipital plate 210, and may be adjusted positionally priorto locking. For example, clamping assembly 220 may be repositionedlaterally by sliding clamping assembly 220 along a portion of occipitalplate 210. For another example, clamping assembly 220 may berepositioned rotationally by turning clamping assembly 220 about an axissubstantially orthogonal to occipital plate 210. In its unlocked state,clamping assembly 220 may be prevented from disconnecting completelyfrom occipital plate 210, for example by a retaining element onoccipital plate 210 or on clamping assembly 220. In some embodiments, anunlocked clamping assembly 220 may be fully disconnected from occipitalplate 210. Furthermore, some embodiments of clamping assembly 220 may beconfigured with a loading component to positionally stabilize unlockedclamping assembly 220, allowing for more precise positioning prior tolocking.

Once clamping assembly 220 is properly positioned, clamping assembly 220may be locked in place. Once locked, clamping assembly 220 is rigidlyfixed to occipital plate 210, and further lateral and rotationalmovement of clamping assembly 220 relative to occipital plate 210 isprecluded. Locking occurs when a stabilizing rod (not shown) is insertedinto clamping assembly 220. The adjustability of clamping assembly 220relative to occipital plate 210 prior to locking, along with thesimplicity of the locking procedure, allows each installation ofoccipito-cervical fixation assembly 200 to be quickly and easilycustomized to accommodate variations in patient anatomy as well asvariations in desired therapeutic benefits.

An embodiment of occipital plate 110 is illustrated in FIG. 3. Occipitalplate 110 may be of any size and shape appropriate for securing to anocciput, and may be made from any material suitable for implantationinto the body, such as stainless steel, titanium, ceramic, PEEK, or acomposite material. Grooves 310 may be scored into the top and/or bottomsurfaces of occipital plate 110 to provide for easier and more precisecontouring and reshaping of occipital plate 110. Such grooves 310 mayallow better correlation with the surface of the occiput. Grooves 310may be of varying length, width, and depth, and may run laterally,longitudinally, or in any other direction. Although FIG. 3 illustratesoccipital plate 110 with multiple grooves 310, an occipital plate 110with a single groove 310 or no grooves 310 is contemplated.

As shown in FIG. 3, multiple apertures 320 may be located on occipitalplate 110. One or more such apertures may be arranged in anyconfiguration across occipital plate 110. Such apertures may penetrateboth the top and bottom surfaces of occipital plate 110, and may providefor attachment of occipital plate 110 to the occiput with bone fasteners(not shown) such as bone screws, pins, staples, or any other appropriatefasteners. An aperture 320 may be circular, oval, polygonal, or anyother shape about a center axis that is suitable to accommodate anappropriate fastener. Furthermore, the center axis of an aperture 320may be orthogonal to the surface of occipital plate 110, such that abone faster seated within aperture 320 enters the occiput orthogonally,or the center axis of an aperture 320 may be non-orthogonal to thesurface of occipital plate 110, such that a bone faster seated withinaperture 320 enters the occiput at an acute angle, providing for morecontact between bone and fastener. In addition, aperture 320 may becountersunk such that the head of a bone fastener seated within aperture320 is flush with or recessed from the top surface of occipital plate110. Aperture 320 may also be counter-bored or otherwise shaped toaccommodate a variety of bone fasteners. Multiple apertures 320distributed across occipital plate 110 may be of uniform size and shapeor may be of variable size and shape.

It is contemplated that occipital plate 110 may not utilize anyapertures 320. In such embodiments, other methods of securing theoccipital plate to the occiput are employed. For example, the occipitalplate may be secured to the occiput with an adhesive, or fixationelements that penetrate the occiput may be integrated with the occipitalplate, thereby eliminating the need for separate bone fasteners.Furthermore, notches or other guide features for interfacing withinstruments external to occipital plate 110 may be located on occipitalplate 110. Such instrument interfaces may allow a tool to be attached tofacilitate placement, adjustment, and other manipulation of occipitalplate 110.

As shown in FIG. 3, a rail 330 for supporting a clamping assemblyextends laterally from each side of occipital plate 110. Apertures 320may be located on the distal portion of occipital plate 110, laterallyextending rails 330 may be located proximally. Although FIG. 3illustrates an embodiment with two laterally extending rails,embodiments with a single rail and embodiments with three or more railsare contemplated. Frictional surface 340 is provided on the bottomsurface of each laterally extending rail 330. In some embodiments,frictional surface 340 may be recessed relative to the bottom surface ofrail 330 and/or relative to the bottom surface of occipital plate 110.

An embodiment of clamping assembly 120 is illustrated in FIG. 4.Clamping assembly 120 may be of any size and shape appropriate forsecuring a stabilizing rod to an occipital plate, and may be made fromany material suitable for implantation into the body, such as stainlesssteel, titanium, ceramic, PEEK, or a composite material. Clampingassembly base component 410 comprises frictional surface 420 andelements 480 for connecting to clamping assembly body component 430.Clamping assembly body component 430 comprises channel 450, lockingthreads 460, and protrusions 470 for connecting to clamping assemblybase component 410. To construct an embodiment of clamping assembly 120,locking component 440 may be positioned within a receptacle of bodycomponent 430, and frictional surface 420 of clamping assembly basecomponent 410 may be positioned against frictional surface 340 of rail330. Body component 430 may then be united with base component 410 suchthat locking component 440 contacts rail 330. Body component 430 andbase component 410 may then be secured together, for example by a weldapplied between protrusions 470 and elements 480 or other suitable meansof rigidly connecting those components; however, other suitable methodsof securing body component 430 and base component 410 are contemplated.As shown in FIG. 4, one or more of the elements 470 may be positioned onopposing sides of rail 330, thereby allowing clamping assembly 120 arange of rotational movement.

As constructed, clamping assembly 120 in its unlocked state looselyencloses a portion of rail 330 and may be repositioned by slidingclamping assembly 120 along a portion of rail 330. In some embodiments,clamping assembly 120 may be repositioned at discrete points along rail330; in other embodiments, clamping assembly 120 may be infinitelyrepositionable along rail 330. In some embodiments, clamping assembly120 may be slid off the end of rail 330 and thus fully disconnected fromrail 330 even after body component 430 and base component 410 aresecured together. In other embodiments, clamping assembly 120 may beslid between two locations along rail 330 but a retaining element mayprevent clamping assembly 120 from sliding off the end of rail 330 afterbody component 430 and base component 410 are secured together.

In its unlocked state, clamping assembly 120 may also be repositionedrotationally after body component 430 and base component 410 are securedtogether. Such rotational repositioning allows for varying the angle atwhich a stabilizing rod inserted in channel 450 is positioned relativeto rail 330. In the embodiment shown in FIG. 4, the degree of possiblerotational repositioning depends on the difference between the width ofrail 330 and the distance between connection elements 470. The smallerthe width of rail 330 relative to the distance between connectionelements 470, the more rotational repositioning is possible. In someembodiments, clamping assembly 120 may be rotationally repositioned in afinite number of positions; in other embodiments, clamping assembly 120may be infinitely rotationally repositioned.

Both the lateral and rotational position of clamping assembly 120 may belocked by introducing a stabilizing rod (not shown) into channel 450.Locking threads 460 prevent the stabilizing rod from exiting channel450, and in some embodiments a locking nut, locking cap, or othercomponent (not shown) may be employed to secure the stabilizing rod inchannel 450. In some embodiments, clamping assembly 120 is still fullyor partially adjustable after the insertion of the stabilizing rod, butnot after the stabilizing rod is fully secured. Exemplary apparatus thatmay be utilized to lock the rod within channel 450 are described in U.S.Pat. No. 6,540,748 and U.S. Published Patent Application Nos.2010/0256681 and 2006/0235392, each of which is owned by BlackstoneMedical, Inc. and are hereby incorporated by reference.

A secured stabilizing rod in channel 450 contacts and exerts a forceupon locking component 440, causing locking component 440 to exert aforce upon the top surface of rail 330, pulling frictional surface 420of clamping assembly base component 410 into contact with frictionalsurface 340 of rail 330. This immobilizing force locks the position ofclamping assembly 120 both laterally and rotationally, effectivelylocking the position of the stabilizing rod relative to the occipitalplate with no direct contact between the stabilizing rod and frictionalsurface 340. In the embodiment of FIG. 4, locking component 440 is arod-to-plate locking pin located between clamping assembly bodycomponent 430 and rail 330. When a rod is inserted in clamping assembly120, the rod presses on the locking pin causing pressure on rail 330,thus pulling the frictional surface of clamping assembly 120 into thefrictional surface of rail 330, thus locking the rod to the rail.

An embodiment of occipital plate 210 is illustrated in FIG. 5. Occipitalplate 210 may be of any size and shape appropriate for securing to anocciput, and may be made from any material suitable for implantationinto the body, such as stainless steel, titanium, ceramic, or acomposite material. Grooves 510 may be scored into the top and/or bottomsurfaces of occipital plate 210 to provide for easier and more precisecontouring and reshaping of occipital plate 210. Such grooves 510 mayallow better correlation with the surface of the occiput. Grooves 510may be of varying length, width, and depth, and may run laterally,longitudinally, or in any other direction. Although FIG. 5 illustratesoccipital plate 210 with multiple grooves 510, an occipital plate 210with a single groove 510 or no grooves 510 is contemplated.

As shown in FIG. 5, multiple apertures 520 may be located on occipitalplate 210. One or more such apertures may be arranged in anyconfiguration across occipital plate 210. Such apertures may penetrateboth the top and bottom surfaces of occipital plate 210, and may providefor attachment of occipital plate 210 to the occiput with bone fasteners(not shown) such as bone screws, pins, staples, or any other appropriatefasteners. An aperture 520 may be circular, oval, polygonal, or anyother shape about a center axis. Furthermore, the center axis of anaperture 520 may be orthogonal to the surface of occipital plate 210,such that a bone faster seated within aperture 520 enters the occiputorthogonally, or the center axis of an aperture 520 may benon-orthogonal to the surface of occipital plate 210, such that a bonefaster seated within aperture 520 enters the occiput at an acute angle,providing for more contact between bone and fastener. In addition,aperture 520 may be countersunk such that the head of a bone fastenerseated within aperture 520 is flush with or recessed from the topsurface of occipital plate 210. Aperture 520 may also be counter-boredor otherwise shaped to accommodate a variety of bone fasteners. Multipleapertures 520 distributed across occipital plate 210 may be of uniformsize and shape or may be of variable size and shape.

It is contemplated that occipital plate 210 may not utilize anyapertures 520. In such embodiments, other methods of securing theoccipital plate to the occiput are employed. For example, the occipitalplate may be secured to the occiput with an adhesive, or fixationelements that penetrate the occiput may be integrated with the occipitalplate, thereby eliminating the need for separate bone fasteners.Furthermore, notches 550 or other guide features for interfacing withinstruments external to occipital plate 210 may be located on occipitalplate 210. Such instrument interfaces may allow a tool to be attached tofacilitate placement, adjustment, and other manipulation of occipitalplate 210.

As shown in FIG. 5, a rail 530 for supporting a clamping assemblyextends laterally from each side of occipital plate 210. Apertures 520may be located on the distal portion of occipital plate 210, laterallyextending rails 530 may be located proximally. Although FIG. 5illustrates an embodiment with two laterally extending rails,embodiments with a single rail and embodiments with three or more railsare contemplated. Frictional surface 540 is provided on the bottomsurface of each laterally extending rail 530. In some embodiments,frictional surface 540 may be recessed relative to the bottom surface ofrail 530 and/or relative to the bottom surface of occipital plate 210.

An embodiment of clamping assembly 220 is illustrated in FIG. 6A. Across-sectional view of this embodiment is illustrated in FIG. 6B.Clamping assembly 220 may be of any size and shape appropriate forsecuring a stabilizing rod to an occipital plate, and may be made fromany material suitable for implantation into the body, such as stainlesssteel, titanium, ceramic, or a composite material. Clamping assemblybase component 610 comprises frictional surface 620, opening 685 intoball channel 686, and aperture 670. Clamping assembly body component 630comprises channel 650, dimples 680, and locking threads 660. Toconstruct an embodiment of clamping assembly 220, rail 530 may beinserted through clamping assembly base component aperture 670 such thatfrictional surface 620 of clamping assembly base component 610 is incontact with frictional surface 540 of rail 530. Locking component 640may be positioned within a receptacle of body component 630. Accordingto one embodiment, the locking component may have a saddle-shapedsurface adapted for contacting the stabilizing rod with a larger surfacearea than a rounded surface. Body component 630 may then be united withbase component 610 such that locking component 640 contacts rail 530.Dimple 680 may then be aligned with opening 685 of clamping assemblybase component 610 for insertion of a ball 690 into ball channel 686.Body component 630 may then be rotated until the next dimple 680 isaligned with opening 685 for insertion of another ball 690 until eachdimple 680 is occupied by a ball 690. Each of the balls 690 mayinterface with the ball channel 686 once it has been installed into thebody component 630, thereby allowing the body component to rotate withrespect to the base component 610. Once all of the balls 690 have beeninstalled, a cap or closing screw may be inserted into opening 685, thuspreventing the balls 690 from falling out of the clamping assembly 220during rotational movement of the body component 630 with respect to thebase component 610.

As constructed, clamping assembly 220 in its unlocked state looselyencloses a portion of rail 530 and may be repositioned by slidingclamping assembly 220 along a portion of rail 530. In some embodiments,clamping assembly 220 may be repositioned at discrete points along rail530; in other embodiments, clamping assembly 220 may be infinitelyrepositionable along rail 530. In some embodiments, clamping assembly220 may be slid off the end of rail 530 and thus fully disconnected fromrail 530 even after body component 630 and base component 610 aresecured together. In other embodiments, clamping assembly 220 may beslid between two locations along rail 530 but a retaining element 695may prevent clamping assembly 220 from sliding off the end of rail 530.

In its unlocked state, clamping assembly 220 may also be repositionedrotationally after body component 630 and base component 610 are securedtogether. Such rotational repositioning allows for varying the angle atwhich a stabilizing rod inserted in channel 650 is positioned relativeto rail 530. In the embodiment shown in FIGS. 6A and 6B, the method ofsecuring body component 630 to base component 610 provides for infiniterotational repositioning, since ball channel 686 allows body component630 to freely rotate within base component 610. In some embodiments,clamping assembly 220 may be rotationally repositioned in a finitenumber of positions. In some embodiments, clamping assembly 220 may beinfinitely rotationally repositioned within a limited range.

Both the lateral and rotational position of clamping assembly 220 may belocked by introducing a stabilizing rod (not shown) into channel 650.Locking threads 660 prevent the stabilizing rod from exiting channel650, and in some embodiments a locking nut, locking cap, or othercomponent (not shown) may be employed to secure the stabilizing rod inchannel 650. In some embodiments, clamping assembly 220 is still fullyor partially adjustable after the insertion of the stabilizing rod, butnot after the stabilizing rod is fully secured.

A secured stabilizing rod in channel 650 contacts and exerts a forceupon locking component 640, causing locking component 640 to exert aforce upon the top surface of rail 530, pulling frictional surface 620of clamping assembly base component 610 into contact with frictionalsurface 540 of rail 530. This immobilizing force locks the position ofclamping assembly 220 both laterally and rotationally, effectivelylocking the position of the stabilizing rod relative to the occipitalplate with no contact between the stabilizing rod and frictional surface540. In the embodiment of FIGS. 6A and 6B, locking component 640 is arod-to-plate locking pin located between clamping assembly bodycomponent 630 and rail 530. When a rod is inserted in clamping assembly220, the rod presses on the locking pin causing pressure on rail 530,thus pulling the frictional surface of clamping assembly 220 intocontact with the frictional surface of rail 530, thus locking the rod tothe rail.

In some embodiments, a loading component may exert a stabilizing forceon the locking component to keep the clamping assembly positionallystable prior to locking. Such a loading component allows for moreprecise lateral and rotational positioning of the clamping assembly. Inthe embodiment illustrated in FIGS. 6A and 6B, loading component 699 isrepresented by a wave spring located between clamping assembly bodycomponent 630 and locking component 640. The wave spring exerts a lightpressure on locking component 640 to act as a load to the system. Thisload imparts a friction to the system, keeping the clamping assemblypositionally stable. Although a wave spring is depicted in FIGS. 6A and6B, other suitable methods of loading the system are contemplated.

According to some embodiments, the disclosed assembly may be connectedto one or more rods that are also connected to one or more cervicalvertebrae. These rods may be connected to the cervical vertebra throughthe use of pedicle screws, such as the screws described in U.S. Pat. No.6,540,748 and U.S. Published Patent Application No. 2010/0256681, bothof which are owned by Blackstone Medical, Inc. and which areincorporated herein by reference.

Although the present invention has been described in detail, it shouldbe understood that various changes, substitutions, and alterations canbe made without departing from the spirit and scope of the invention asdefined by the appended claims. Various terms used herein have specialmeanings within the present technical field. Whether a particular termshould be construed as such a “term of art” depends on the context inwhich that term is used. “Connected to,” “coupled to,” “secured to,” “incontact with,” or other similar terms should generally be construedbroadly. These and other terms are to be construed in light of thecontext in which they are used in the present disclosure and as thoseterms would be understood by one of ordinary skill in the art wouldunderstand those terms in the disclosed context. The above definitionsare not exclusive of other meanings that might be imparted to thoseterms based on the disclosed context.

Words of comparison, measurement, and timing such as “at the time,”“equivalent,” “during,” “complete,” and the like should be understood tomean “substantially at the time,” “substantially equivalent,”“substantially during,” “substantially complete,” etc., where“substantially” means that such comparisons, measurements, and timingsare practicable to accomplish the implicitly or expressly stated desiredresult.

Additionally, the section headings herein are provided for consistencywith the suggestions under 37 C.F.R. 1.77 or otherwise to provideorganizational cues. These headings shall not limit or characterize theinvention(s) set out in any claims that may issue from this disclosure.Specifically and by way of example, although the headings refer to a“Technical Field,” such claims should not be limited by the languagechosen under this heading to describe the so-called technical field.Further, a description of a technology in the “Background” is not to beconstrued as an admission that technology is prior art to anyinvention(s) in this disclosure. Neither is the “Summary” to beconsidered as a characterization of the invention(s) set forth in issuedclaims. Furthermore, any reference in this disclosure to “invention” inthe singular should not be used to argue that there is only a singlepoint of novelty in this disclosure. Multiple inventions may be setforth according to the limitations of the multiple claims issuing fromthis disclosure, and such claims accordingly define the invention(s),and their equivalents, that are protected thereby. In all instances, thescope of such claims shall be considered on their own merits in light ofthis disclosure, but should not be constrained by the headings herein.

We claim:
 1. An implantable orthopedic assembly comprising: an occipitalplate comprising a top surface and a bottom surface, the bottom surfaceof the occipital plate adapted for securing to an occiput; at least onerail extending laterally from a proximal portion of the occipital plate,the at least one rail comprising a top surface and a bottom surface, thebottom surface of the rail comprising a frictional surface; and at leastone repositionable clamping assembly adapted to enclose a portion of theat least one rail, the clamping assembly further adapted for securing aportion of a stabilizing rod at a distance from the frictional surfaceof the at least one rail, the clamping assembly comprising: a basecomponent comprising a frictional surface, the frictional surface of thebase component adapted to contact the frictional surface of the at leastone rail, the base component further adapted for lateral repositioningbetween a first rail position and a second rail position; a bodycomponent adapted to be rigidly coupled to the base component, the bodycomponent further adapted for repositioning between a first rotationalposition and a second rotational position, the body component furtheradapted to receive the portion of the stabilizing rod; and a lockingcomponent adapted to contact the body component when the body componentis in contact with the top surface of the at least one rail, and is alsoin contact with the received portion of the stabilizing rod, the lockingcomponent adapted to transfer an immobilizing force from the receivedportion of the stabilizing rod to the top surface of the at least onerail, the immobilizing force immobilizing the clamping assembly at afixed rail position and in a fixed rotational position.
 2. Theimplantable orthopedic assembly of claim 1, wherein the occipital platefurther comprises at least one groove scoring at least one of the topsurface of the occipital plate or the bottom surface of the occipitalplate, the at least one groove adapted to facilitate contouring of theoccipital plate.
 3. The implantable orthopedic assembly of claim 2,wherein the at least one groove comprises a first groove and a secondgroove, the second groove substantially orthogonal to the first groove.4. The implantable orthopedic assembly of claim 1, wherein a pluralityof apertures is variably distributed across the occipital plate, whereinthe plurality of apertures penetrates both the top surface of theoccipital plate and the bottom surface of the occipital plate, andwherein at least one of the plurality of apertures is adapted to receiveat least one bone fastener, the at least one bone fastener adapted tosecure the bottom surface of the occipital plate to the occiput.
 5. Theimplantable orthopedic assembly of claim 4, wherein the at least onebone fastener comprises a bone screw.
 6. The implantable orthopedicassembly of claim 4, wherein the plurality of apertures comprises asubstantially circular first aperture centered about a first aperturecenter axis.
 7. The implantable orthopedic assembly of claim 6, whereinthe first aperture center axis is non-orthogonal to at least one of thetop surface of the occipital plate and the bottom surface of theoccipital plate.
 8. The implantable orthopedic assembly of claim 4,wherein at least one of the plurality of apertures comprises acountersunk aperture.
 9. The implantable orthopedic assembly of claim 1,the occipital plate further comprising at least one instrument interfaceadapted to facilitate manipulation of the occipital plate with aninstrument.
 10. The implantable orthopedic assembly of claim 9, whereinthe occipital plate further comprises an edge surface connecting the topsurface of the occipital plate and the bottom surface of the occipitalplate, and wherein the at least one instrument interface comprises anotch in the edge surface of the occipital plate.
 11. The implantableorthopedic assembly of claim 1, wherein the at least one rail comprisesa first rail and a second rail, the first rail extending from a leftside of the occipital plate, the second rail extending from a right sideof the occipital plate.
 12. The implantable orthopedic assembly of claim1, wherein the frictional surface of the at least one rail is recessed.13. The implantable orthopedic assembly of claim 1, wherein the basecomponent of the at least one repositionable clamping assembly isadapted for infinite lateral repositioning between the first railposition and the second rail position.
 14. The implantable orthopedicassembly of claim 1, wherein the body component of the at least onerepositionable clamping assembly is adapted for infinite rotationalrepositioning between the first body position and the second bodyposition.
 15. The implantable orthopedic assembly of claim 1, whereinthe at least one repositionable clamping assembly further comprises aloading component adapted to exert a stabilizing force on the lockingcomponent, the stabilizing force stabilizing the at least onerepositionable clamping assembly at an adjustable rail position and inan adjustable body position.
 16. The implantable orthopedic assembly ofclaim 1, wherein the base component comprises at least one elementadapted to be connected to at least one corresponding protrusion fromthe body component.
 17. The implantable orthopedic assembly of claim 16,wherein the body component comprises two protrusions adapted to beplaced on opposite sides of the at least one rail and the base componentcomprises two corresponding receiving elements into which theprotrusions may be attached.
 18. The implantable orthopedic assembly ofclaim 17, wherein the protrusions are attached to the receiving elementsby a weld.
 19. The implantable orthopedic assembly of claim 17, whereinthe locking component has a rounded upper surface for contacting thereceived portion of the stabilizing rod.
 20. The implantable orthopedicassembly of claim 1, wherein the base component comprises an aperturethat is adapted to enclose a portion of the at least one rail.
 21. Theimplantable orthopedic assembly of claim 1, wherein the clampingassembly further comprises a loading device adapted to be positionedbetween the body component and the locking component.
 22. Theimplantable orthopedic assembly of claim 21, wherein the loading devicecomprises a wave spring.
 23. The implantable orthopedic assembly ofclaim 1, wherein the base component comprises a radial channel on theinterior surface of the base component and an opening aligned with thechannel, and wherein the body component comprises at least one dimplepositioned on the outer surface such that when the base component isconnected to the body component, the at least one dimple can be alignedwith the opening in the base component.
 24. The implantable orthopedicassembly of claim 23, further comprising at least one ball correspondingto each of the at least one dimples, each of said balls adapted to beplaced into the opening and mated with a corresponding dimple when thebase component is connected to the body component, and further whereinthe ball facilitates rotational movement of the body component withrespect to the base component by moving within the radial channel of thebase component while remaining adjacent to the corresponding dimple inthe body component.
 25. The implantable orthopedic assembly of claim 1,wherein the locking component has a saddle-shaped surface for contactingthe received portion of the stabilizing rod.
 26. The implantableorthopedic assembly of claim 20, further comprising a retaining elementthat is adapted to be attached to the rail and prevent the basecomponent from sliding off an end of the rail.
 27. A method ofconstructing an implantable orthopedic assembly comprising an occipitalplate, at least one rail rigidly coupled to and extending laterally fromthe occipital plate, and at least one repositionable clamping assemblyenclosing a portion of the at least one rail, the at least onerepositionable clamping assembly adapted for securing a received portionof a stabilizing rod, the method comprising: positioning a lockingcomponent of the repositionable clamping assembly within a receptacle ofa body component of the at least one repositionable clamping assembly;positioning a frictional surface of the at least one rail against africtional surface of a base component of the at least onerepositionable clamping assembly; uniting the body component with thebase component, wherein the at least one rail contacts the lockingcomponent; and securing the base component to the body component. 28.The method of claim 27, further comprising positioning a loadingcomponent between the locking component and the body component of the atleast one repositionable clamping assembly, wherein the loadingcomponent is adapted to exert a bias on the locking component againstthe at least one rail to stabilizing the at least one repositionableclamping assembly at an adjustable rail position and in an adjustablebody position.